Commonly assigned U.S. Pat. No. 5,599,452 to MacLaren et al. discloses a wastewater treatment method which uses a conventional aspirator design.
U.S. Pat. No. 3,776,531 to Ebner, et al. discloses an apparatus with separate propeller blades and aspirator tubes for dispersing and entraining a fluid, particularly a gas, in a liquid. The reference teaches that the aspirator tubes should be at an angle between 35 degrees and 75 degrees, when compared to the vertical axis of the shaft.
U.S. Pat. No. 5,318,360 to Langer, et al. discloses a gas dispersion stirrer comprising a rotatable shaft and at least one hollow, disk-shaped stirring/aspirating member. This reference teaches the inclusion of flow-inducing blades on both the top side and the bottom side of the disk-shaped member.
The Soviet Union patent SU 1,315,391 shows the utilization of swirlers 13 on the outer edges of the hollow vanes 5.
U.S. Pat. No. 3,779,531 to White shows some aeration tubes that are utilized at a downward angle compared to the vertical shaft.
The Japanese patent JP 63-028432 shows inclined aeration tubes in FIGS. 1 and 3.
U.S. Pat. No. 1,380,970 to Meridith-Jones shows the utilization of rods to break up liquid.
U.S. Pat. No. 1,124,855 to Callow, et al. shows angled aeration tubes 13 in FIG. 1.